Quoting from the email thrown around between kirk, bde and iedowse@..

<QUOTE>
Overflow of cg_niblk causes spurious "SUMMARY INFORMATION BAD" warnings
prompts in fsck_ffs. cg_niblk has type int16_t, but it is (ab)used
to hold the number of inodes per group (it has nothing to do with the
number of inode blocks in the cg as claimed in ffs/fs.h), and there
can be lots of inodes per group. E.g.,

newfs -i 8192 -b 16384 -f 16384 -c 255 ...

gives 0xA900 inodes/group. Assignment of this to cg_niblk gives
-0x5700. This is mostly harmless (ufs/ffs doesn't use cg_niblk, and
bug-for-bug compatible overflow occurs in newfs), but in
fsck_ffs/pass5.c, negative values of cg_niblk limit cg_irotor to 0
and the summary info appears to be bad.
</QUOTE>

Submitted by: Bruce Evans <bde@zeta.org.au>
Obtained from: Kirk McKusick <mckusick@mckusick.com>